Dual-Scale Polarization Engineering of <scp>d</scp>-Phenylalanine-Based Assemblies for High-Performance Nanogenerators

Piezoelectric biomaterials hold immense potential for next-generation microdevices, yet their piezoelectric performance often trails behind that of conventional synthetic counterparts. This study demonstrates a dual-scale polarization strategy to significantly enhance the piezoelectric response of d-phenylalanine derivatives (d-PheAD). Molecular-level polarization is amplified through ionic interactions with l-glutamic acid-modified Fe₃O₄ magnetic nanoparticles, while macroscopic alignment of d-PheAD nanoarrays under magnetic fields optimizes collective dipole orientation. This synergistic approach elevates the effective piezoelectric coefficient (<i>d</i>_eff) from 10.4 to 121.9 pm V^-1, outperforming most biomaterial-based piezoelectric systems and many inorganic piezoelectric systems. Integrating these engineered assemblies into a triboelectric-enhanced piezoelectric nanogenerator yields unprecedented electrical outputs (2853 nA, 51.9 V), a 25-fold improvement over baseline configurations. The device achieves real-time detection of trace HCl gas at low concentrations, demonstrating superior sensitivity compared to commercial electrochemical sensors. By bridging molecular design and macroscopic engineering, this work establishes a scalable paradigm for deploying eco-friendly piezoelectric biomaterials in high-performance microelectronics and environmental monitoring technologies.